The present invention relates to chairs, and in particular to a chair which enables the occupant to be seated with correct posture. The invention also provides a novel method of assembly for a chair.
An occupant of a chair seated with correct posture should have his or her back relatively straight with the spine having a slight bow at its lower portion. Correct posture can prevent and alleviate back pain. To this end, chair designs have been continually refined in order to ensure that the occupant is seated with the correct posture to minimise and hopefully eliminate back pain. While the perfect chair has yet to be invented substantial strides have been made and continue to be made.
Various attempts have been made to design a chair that will ensure correct posture and one such chair has been invented by the subject inventor and is disclosed in U.S. Pat. No. 4,889,387. The chair in question, while very satisfactory, is sufficiently costly that it does not lend itself to being used in chair that is priced sufficiently low to reach a mass market and thus provide the desired benefit to a wide range of consumers. In essence there has long been a need to provide a relatively low cost chair that will maintain a sitter in the desired correct posture while resisting forward movement of the sitter from the seat.
It is therefore an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
In accordance with a first aspect of the invention there is provided a chair having a seat assembly for supporting a person sitting on the chair, the seat assembly including:
a seat frame;
sheet material that is stretched and secured in place relative to said frame to support the weight of a person sitting on the chair by tension forces in the sheet material;
said sheet material including a bead along an edge thereof, said seat frame including an extruded section with a recess into which said bead is located,
wherein said bead is secured in said recess by means of a retaining member so as to secure said sheet material under tension to said seat frame.
Preferably the retaining member for securing the bead portion within said recess includes a tongue portion which is shaped and sized so as to locate within the recess and retain the bead in place in said recess. It is further preferable that the retaining member is of constant cross-sectional profile along its length. Preferably the retaining member is substantially T-shaped. It is also preferable that the retaining member is extruded.
Preferably the extruded section of the seat frame is made from aluminium or aluminium alloy.
Preferably the sheet material includes a bead along at least a pair of opposing edges, said bead being located and retained in said recess of said extruded section to secure said sheet material in place relative to said frame. Preferably the sheet material is woven. It is further preferable that the sheet material is woven from polyester elastomeric fibres.
In accordance with a second aspect of the invention there is provided a method of securing a sheet material to a seat frame so as to form a support portion,
said sheet material including a bead along an edge thereof,
said seat frame including an extruded section with a recess into which said bead is located,
the method comprising steps of stretching the sheet material to the desired length in order that said bead may be located in said recess, locating said bead in said recess, and securing the bead in said recess by means of a retaining member so as to secure said sheet material under tension to said seat frame.
Preferably the sheet material is located in one or more clamps and subsequently stretched to the desired length in order to locate said bead portion in said recess.
Preferably, the sheet material includes a bead along at least a pair of opposing edges, the bead being located and retained in the recess of the extruded section so as to secure the sheet material in place relative to said frame. Preferably, the bead is retained in the recess by a retaining member which includes a tongue adapted to locate within the recess and thereby retain the bead in the recess.
Preferably, the sheet material is woven. In one preferred embodiment the front support portion is woven with more fibres per inch than said rear support portion. In one preferred embodiment the sheet material is woven from polyester elastomeric fibres.
Unless the context clearly requires otherwise, throughout the description and the claims, the words xe2x80x98comprisexe2x80x99, xe2x80x98comprisingxe2x80x99, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of xe2x80x9cincluding, but not limited toxe2x80x9d.
The present invention provides a novel chair construction that is capable of having all the desired movements including seat height and tilt adjustment, synchronised back and seat angle adjustment and incorporates a novel seat construction that provides posture support. In a preferred embodiment the support portion of the seat is composed of sheet material, preferably woven fabric or mesh material, having a front support portion that is more resistant to deformation than its rear support portion. In one embodiment the front portion is woven with more fibres per inch than the rear support portion. In another embodiment, the front support portion is stretched to a greater extent than the rear support portion such that the front support portion is less compliant than the rear support portion. The front support portion and the rear support portion may be formed from a unitary sheet material. A sheet with the desired dual compliance may be formed of separate sections of fibre that are woven together to form a single fabric. Prior to installation in the seat frame the sheet is stretched and while in its stretched condition is inserted into recesses in the seat frame and maintained in the stretched condition by suitable retaining members.